Cylinder Liner Recess Layout for Low-Friction, Low-Oil-Use Sliding
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Solution Overview
Problem
The dimple liner technique for reducing friction in internal combustion engines improves fuel efficiency but increases oil consumption, and existing solutions fail to optimize both simultaneously.
Innovation Solution
A sliding structure with recesses on the cylinder liner and inclined surfaces on the piston rings, allowing fluid lubrication and controlling friction coefficients to minimize oil consumption while maintaining fuel efficiency, by forming recesses in the stroke center region and maintaining a smooth region outside it, with specific friction coefficient ratios and surface configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If recesses are formed in the stroke center region to reduce friction and improve fuel efficiency, then fuel efficiency is improved, but oil consumption increases
Solution Approach 1:
The invention applies different surface treatments to different regions of the cylinder liner. The stroke center region has recesses formed to reduce friction during high-speed operation, while the top dead center region maintains a smooth surface. This local differentiation allows the system to optimize for fuel efficiency in the stroke center region without causing excessive oil consumption at the top dead center region, thereby resolving the contradiction between fuel efficiency and oil consumption.
2Force
If recesses are formed in the stroke center region, then sliding resistance is reduced, but lubrication performance deteriorates
Solution Approach 1:
The invention implements local quality by forming recesses only in the stroke center region where sliding resistance needs reduction, while maintaining a smooth surface in the top dead center region where proper lubrication is critical. This spatial differentiation of surface characteristics allows the system to reduce sliding resistance where needed without compromising lubrication performance where it is most important.
Solution Approach 2:
The cylinder liner surface is segmented into two distinct regions: a stroke center region with recesses for reducing friction, and a top dead center region with a smooth surface for maintaining lubrication. This segmentation allows each region to be optimized independently for its specific functional requirements, resolving the contradiction between reducing sliding resistance and maintaining lubrication performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces oil consumption while maintaining or improving fuel efficiency by optimizing friction coefficients and lubrication across different operational regions of the engine, providing a balanced solution to the limitations of previous techniques.
Implementation Method 1
both outer edges of an outer circumferential surface thereof in an axial direction opposed to the inner wall surface are provided with inclined surfaces that can be in contact with the inner wall surface while being inclined away from the inner wall surface outwardly in the axial direction, and a lubricating oil flows into a gap between the inner wall surface and the outer circumferential surface that relatively move via the inclined surfaces, thereby enabling fluid lubrication
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
Regarding a sliding structure for an internal combustion engine of the present invention, a cylinder has a plurality of recesses formed in a stroke center region. Piston rings are configured to have inclined surfaces formed on an outer circumferential surface thereof, and a lubricating oil flows into a gap between the inner wall surface and the outer circumferential surface that relatively move via the inclined surfaces, thereby enabling fluid lubrication. At any RPM equal to or greater than an RPM for an idling operation of the internal combustion engine, a friction coefficient (hereafter, a center friction coefficient) at a place of the stroke center region through which the piston rings pass at the highest speed is set to be less than a center friction coefficient when it is assumed that the recesses are not formed in the stroke center region. On the other hand, at the RPM, a friction coefficient (hereafter, an outside friction coefficient) when the piston rings pass through any place in an outside region that is outside the stroke center region is set to be less than an outside friction coefficient when it is assumed that the plurality of recesses are formed in the outside region. As a result, it is possible to achieve further improved low fuel efficiency for the dimple liner technique.